Sorry for this super noob question, but what does a head do ?? and whats the difference b/w head and a combo for amps??

Head = Amplifer
Cabinet = Speakers

Combo = Head and Cabinet together in one package.

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Quote by utsapp89
^I'd let a pro look at it. Once you get into the technicalities of screws...well, it's just a place you don't want to be, friend.

Usually a combo will only be a 1x12" or 2x12" speaker, not always.
Cabinets can be anywhere from 1x12s to 6x12s.

More speakers push more air. Disperse sound better, sound a bit louder, and have more clarity and low end.

Cabinet construction also affects sound quality. A well made 1x12 cabinet with a closed back (combos usually have open backs to keep the amp cool), would sound better and have a stronger low end than a run of the mill combo.

A half stack set up means its easier to mix and match your speakers, you can buy a new head for cheaper than a combo, so you can always hold onto the cab if you want to upgrade. In some cases, its easier to carry. A head and a 2x12 cabinet would be easier to carry than a 2x12 combo.

And for the record. You cannot operate a head without a cabinet.
it's also a tiny detail, but in a head, the tubes aren't as close to the speakers as on a combo, which means they will not rattle because of the vibrations in the speaker. This can increase a bit the lifetime of the toobz, but it's just a detail, and it doesn't really matter.

head and cab is +1 for the cool factor though, but when I gig, I never carry my heads and cabs, too much of a ***** to carry, I just bring a Fender Twin or a Traynor YCV, sounds great and isn't too heavy =)